Comment 0 for bug 1771704

Per https://bugs.launchpad.net/ubuntu/+source/avahi/+bug/1717983, link-local address support was previously handled via integration between avahi-autoipd and dhclient. systemd-networkd does not invoke dhclient. It also has direct support for configuring link-local ipv4 addresses. But this support is not enabled by default.

It should be possible for a system configured via netplan to make use of link-local ipv4 addresses, without needing to configure systemd-networkd directly.

Historically we do not turn on link-local ipv4 support automatically on servers (avahi-autoipd not installed by default), and we use link-local addresses only as a fallback when dhcp gives no response. So this should likely not be enabled by default, but instead be exposed as an additional configuration option in netplan yaml.